To the Editor: The results of the study on
Mediterranean diet and mortality by Mr Knoops and colleagues1 may
be confounded by the breadth of the populations that were compared. The analysis
did not control for factors related to national heritage, both cultural and
genetic. In effect, Swedes or Finns consuming one type of diet may have served
as controls for Greeks or Italians consuming another diet. To be valid, studies
of Mediterranean diets should compare diet and lifestyle within Italian or
within Greek populations.